john mcmurtry



" hoister.

Specification forming part of Letters Patent No. 182,215, dated September 12, 1876; application filed July 21, 1876. i

bined as to dispense entirely with both the cog-gear and brakes that are usually employed.

Figure 1 is a front elevation of a hoister embodying my invention. Fig. 2 is a transverse sectional view of same.

A represents the base-plate or foundationpieoe of the frame of the hoister. A represents the cross top-piece thereof. B B represent the posts for guiding the weights mm. c

0 represent the movable platform, of common construction, excepting that it has a sheavepulley on each side of same, marked d d. E is the main shaft, on which are keyed at each end, and inside of the posts A A, sheavewheels ff and g g, of different diameters, and having the grooves around the same made V- shaped, so as to prevent the rope from slipping on same when kept taut with the weights m m. H is the sheave-wheel of the common hoister, attached directly to the end of the main shaft E. Said sheave-wheel may have one or more sheaves attached to its outside, of different diameters, as I, for the purpose of gaining speed.

J J is the main driving-rope operating the k and L are idlers, carrying the ropes from the sheave-wheels f and g connecting with the weights m m. n a are the ropes connecting the sheave-wheels f and g with the platform 0, and operating the same.

Mode of operation Reference being bad to Fig. 2 of the annexed drawing and the above description of same, it will be readily understood that the ropes n a pass around pulleys d din the platform 0, with the rope on the right passing over the sheave-wheel f on the main shaft E, and the rope on the left passing over the smaller sheavewheel gin the opposite direction, and passing around same and down over the idler k, and also around the idler L' on the weight m, and up toward and uniting with the opposite end of the rope from the large sheave-pulley f, thus forming an endless rope around the sheave-pulleys f and g, and connecting with the platform and weights, as described.

Now, it is manifest that to operate the main shaft E by means of the driving-rope J the sheaves f and 9, being of different diameters, would take up and let off the ropes n n unequally and in proportion to their diameters, and cause the platform 0 to he raised and the weights m m to be depressed in a corthus render the usual brakes in hoisters en-' tirely unnecessary.

Fiber ropes, or even wire ropes, over the sheave-wheels and idlers will necessarily work Without friction, and be much freer from accidents than where everything depends on the quality of a single cast-iron cog. and the construction is certainly greatly simplified and oheapened.

This hoister can have attached to it any of the devices desired for protection against the breaking of the ropes or shifting the driving-belts, in case that steam-power is applied.

It will be observed, however, that the breaking of the driving-rope J would not effect any movement in the platform, which would only remain at rest in such an event.

The power of my improved hoister may be increased almost indefinitely by decreasing the difference in the diameters of the sheavewheels f and g on the main shaft E, and the speed-ofthe hoistercan be increased by increasing the difl'erence between the diameters of said sheave-Wheels f and g.

WhatYI claim and desire to secure byLetters Patent, is

The combination of the main shaft E, with v its sheave-wheels f and g, of different diame ters, with the endless ropes n n on same, and

connected with the platform 0, andthe weights 4 in m over and aroundfthe idlersd, L, and 7c," and operated bythe wheel I-,.,0r itSLeqlllValent, On the end of the main shaft E, substantially as described, and for the purpose 

